Sample injection apparatus

ABSTRACT

Syringe-type apparatus for injecting a fluid sample into a fluid stream including a plunger section and a needle section enclosing a sample cavity of predetermined volume and diameter. The cavity includes a discharge opening in the front of the needle section and a gas inlet opening adapted to be opened or closed by a reciprocable plunger in the plunger section of the device. The plunger section also includes a gas inlet port through the sidewall thereof communicating with the inlet opening to the needle section when the plunger is in a retracted position. The needle section has a shoulder formed on the outer surface thereof at a position between the discharge opening and the inlet opening to the cavity. The shoulder is constructed to engage an abutment within a sample port thereby obstructing flow of the gas stream through the port and causing the gas stream to flow through the gas inlet port into the sample injector cavity to sweep the sample from the cavity.

United States Patent [72] Inventor Theron Johns Orange, Calif. [21] Appl. No. 791,265 [22] Filed Jan. 15.1969 {45] Patented Sept. 14. 1971 [73] Assignee Beckman Instruments Inc.

[54] SAMPLE INJECTION APPARATUS 8 Claims, 6 Drawing Figs.

[52] U.S.Cl. 73/422 GC, 23/292, 128/218 [51] Int. Cl G0ln 1/00 [50] Field of Search 73/231, 421 T, 23; 23/232 C. 232. 254, 292; 128/218, 218 C. 218.1. 276, 278

[56] References Cited UNITED STATES PATENTS 1.274.081 7/1918 Riethmueller 128/221 2.771.217 11/1956 Brownetal 73/125.6UX 2.991.647 7/1961 Harris 73/23.l 3.110.310 11/1963 Cislak 128/218C 3.203.455 8/1965 Horabin 128/218 C X 3.327.520 6/1967 Stapp..lr 73/23.1 3.401.692 9/1968 Harris. Jr.... 128/218 C 3.474.674 10/1969 Harris et a1. 73/4254 X FOREIGN PATENTS 1.215.748 4/1960 France ABSTRACT: Syringe-type apparatus for injecting a fluid sample into a fluid stream including a plunger section and a needle section enclosing a sample cavity of predetermined volume and diameter. The cavity includes a discharge opening in the front of the needle section and a gas inlet opening adapted to be opened or closed by a reciprocable plunger in the plunger section of the device. The plunger section also includes a gas inlet port through the sidewall thereof communicating with the inlet opening to the needle section when the plunger is in a retracted position. The needle section has a shoulder formed on the outer surface thereof at a position between the discharge opening and the inlet opening to the cavity. The shoulder is constructed to engage an abutment within a sample port thereby obstructing flow of the gas stream through the port and causing the gas stream to flow through the gas inlet port into the sample injector cavity to sweep the sample from the cavity.

I50. ll

PATENTED SEP 1 4 I9?! SHEEI 1 OF 2 FIG. I

Ail

INVENTOR.

w m m T. HIM T 'PATENJED SEP 1 41am SHEET 2 OF 2 RON JOHNS mvm'mk.

FIG. 4

'llll'llll ATTORNEY SAMPLE INJECTION APPARATUS SUMMARY or THE INVENTION This invention relates to improvements inthe art of injecting fluid samples into a fluid stream and, more particularly, the invention pertains to a device for delivering a reproducible calibrated volume of liquid sample into a carrier gas stream wherein the liquid sample is flash vaporized and flushed by the carrier gas stream into analysis apparatus downstream therefrom.

In stream analysis apparatus, such as gas chromatography equipment, it is necessary to insert a liquid or gaseous sample into a carrier stream or conveyance through the analysis apparatus. The sample is usually introduced as a small sample plug or volume into the, carrier stream and carried through a series of operations and detector devices which provide a quantitative and/or a qualitative measure or indication of the sample constituents. In process type analysis instruments, sample valves are usually employed for injecting a sample from a sample stream into the instrument. In laboratory type analysis instruments, the sample is most commonly introduced with a gas or liquid syringe through a septum inlet in order to provide greater versatility regarding sample sizes and preparation of the sample.

7 In a gas chromatograph, a liquid sample is usually introduced into a heated chamber ahead of the column or directly into the column where the sample is immediately vaporized. The sample is then carried by the stream through the gas chromatograph columns and thence into the detector of the instrument which measures a physical characteristic of the sample constituents as they engage the detector. In using common hypodermic needle syringes and pipette-type sampling devices for injecting the sample into the carrier stream, the accuracy, precision and reproducibility of results suffer because of the variability in injection times, variations in the quantities of injected samples and the uneven vaporization of the sample within the vaporization chamber. A further problem results from the fractionation effect of the sample within the injection needle itself. Fractionation within the needle cavity occurs because a portion of the sample injected by the hypodermic syringe or needle remains in the sample chamber of the syringe. The fractionation effect within the sample injection needle becomes a particularly serious problem when very small samples are introduced into the system and when both high and low boiling components are found as constituents of the sample. It has been observed that a relatively higher percentage of the higher boiling components are left behind in the heated needle while the low boiling components tend to boil OE and eject from the needle during the injection-vaporization step. This is an extremely difficult source of error especially when small volume samples are employed. 4

Another problem which is extremely serious with regard to pipette and syringe-type injectors is the blow back effect and its relationship to base line stability. When a liquid sample is injected into a heated inlet and rapidly vaporized, it undergoes a volume expansion which is dependent on the temperature of the inlet, molecular weight of the sample and the gas pressure in the inlet. The expansion involved is generally in the range of I to 500 fold. This causes a momentary increase in pressure at the point where the sample is vaporized and a flow in all directions. Ideally, it is desirable to have all of the sample flow downstream into or in the column. However, a small portion of the sample will flow upstream. Upstream flow of sample is undesirable for two reasons. It broadens the sample injection volume and, therefore, decreases resolution. Additionally, some of the sample may flow upstream and condense or be absorbed on reduced temperature surfaces. This fraction of the sample will gradually vaporize into the carrier gas and become a source of baseline drift or instability when it reaches the detector. This problem is particularly disturbing in programmed temperature gas chromatography because it may actually cause false peaks.

Accordingly, it is an object of the present invention to provide a sample injection apparatus which causes all of the sam ple within the device injected into the fluid stream to expand in a downstream direction.

Another object of the invention is to provide a sample injection apparatus adapted for injection of extremely small samples in the order of one microliter or less which apparatus eliminates the fractionation effect.

Further objects and advantages of the invention will become apparent as the description proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention, reference may be had to the accompanying drawings in which:

FIG. 1 is a cross-sectional view of one embodiment of the sample injector of the present invention;

FIG. 2 is an enlarged cross section of the inlet to the sample cavity, plunger and the carrier stream inlet port;

FIG. 3 is a greatly enlarged cross section illustrating another embodiment of the needle section of the sample injection device of the present invention;

FIG. 4 is a somewhat schematic illustration of a gas chm matograph system showing one type of sample vaporization inlet with the sample injection device of the present inventio inserted therein;

FIG. 5 is a cross-sectional view of another embodiment of the invention in which the plunger is spring loaded and operated by a hand lever", and

FIG. 6 illustrates another embodiment of an injection chamber formed of a tubular member having a pinched in or rolled shoulder adapted to seal against the respective shoulder on the injection device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, in FIG. 1 there is shown one embodiment of the sample injector apparatus of the present invention comprising a longitudinal tubular member of cylinder 10 having a forward injector section 11 and a rearward plunger section 12. The cylindrical injection device may be formed of stainless steel, Pyrex glass or some other wellknown high temperature resistant material. It should be understood that the relative dimensions of the device, as illustrated in the drawings, are not accurate, but are purposely made of a size sufficient to easily show the relationship and operation of the respective parts.

The forward injector section 11 includes a pointed or narrow needle end adapted to penetrate through a rubber or plastic septum cap, which is normally used to cover a sample inlet and which is normally used in closing bottle samples. The forward or injector section 11 is provided with a sample cavity 13 having a front or outlet opening 14 and a rear or inlet opening 16 adjacent the plunger section of the device. The volume of the sample cavity may be extremely small so that it is adapted to handle small samples in the order of l microliter or less.

The plunger section of the device is provided with an axial cavity or bore 17 aligned with the sample cavity 13 in the injection section of the device. Slidably disposed within the axial cavity 17 is a piston 18 having a forward end or plunger 19 designed to fit snugly within the axial cavity 17 and to slide longitudinally within the cavity. The snugly fitting plunger may be formed of Teflon or other suitable material which provides a low-friction seal with the inner wall of the cavity 17 and prevents back leakage into the rearward portions of the cavity. The plunger 19 may be provided with a pointed or conical valve tip 21, which is aligned with the opening 16 leading from the plunger cavity 17 into the sample cavity 11. Tip 21 is shaped to seat against the shoulder 16a of the opening 16 and effectively seal this opening.

At the lower end of the plunger section 10, there is provided an opening or gas stream inlet port 22 through the sidewall of the cylinder. When the plunger 21 is in a retracted position, as may be seen in FIG. 2, the port 22 is in communication,

through the plunger cavity 17, with the opening 16 to the sample cavity 13.

Means are provided for reciprocating the plunger backward and forwardly within the plunger cavity 17 in order to open and close the opening 16 to the sample cavity 13. These means, in the embodiment shown in FIG. 1, include a mounting block or upper body 26 into which is fitted, by a threaded fit or other means, a threaded support member 27. Seated within the upper body 26 is an O-ring or suitable sealing member 28 which is adapted to fit tightly around the upper end 29 of the piston 18.

In this embodiment of the invention the supporting member 27 is provided with an axial hole or threaded bore having threads which mate with threads formed on upper end 31 of the piston. The piston is screwed into place within the support section 27 with the forward plunger 19 positioned within the plunger cavity 17. The plunger is then turned down into the device so that the tip 21 thereof is positioned adjacent or within the opening 16 to the sample cavity. When the top 18a of the piston is rotated, the tip 21 of the plunger 19 may be moved forward, closing the opening 16 to the sample cavity, or retracted away from the opening 16, permitting communication between the sample cavity and the opening 22 in the sidewall of the plunger section 17. When the support member 27 is threaded into the support body 26, the lower portion 27a abuts against the O-ring 28 forcing the O-ring to seal tightly around the outer circumference of the upper portion 29 of the piston.

The sale injection device of FIGS. 1 and 2 is filled with a sample liquid by retracting the sealing tip 21 of the plunger so that an opening is provided between the opening 16 and port 22 in the sidewall of the injection device. The needle or forward section of the tubular member is inserted into a small bottle or vial which is sealed with a rubber septum so that the opening 14 is below the level of sample liquid within the bottle or vial. A pressure is applied within the bottle or vial by means of gas or other methods to force the sample up the sample tube so that the sample comes out the port 22. When sample liquid immerges through port 22, the sample cavity 13 is completely full. The piston 18 is then screwed down or otherwise depressed so that the tip 21 of the plunger 19 forms a good seal against the sidewall or shoulder 16a of opening 16.

Note that the forward or injection section 11 of the sampling device has formed thereon, between the opening 14 and the opening 16, a shoulder which is of larger diameter than the forward or needle section on the forward end of the device. Shoulder 15 plays a significant part in the use of the device for inserting samples within a sampling system of a flowing fluid stream. While, in the embodiment of FIG. 1, the injector section 11 is formed of two different diameter sections so that the rearward section 150 is merely an extension of shoulder 15, it is obvious that other variations are possible. For example, the shoulder could be formed merely by making an enlarged bead or abutment, such as bead 32 illustrated in the embodiment of FIG. 3. The forward surfaces 15a and 32a of the shoulders 15 and 32 are preferably conical in shape and are adapted to mate with similar shaped surfaces formed within a sample inlet through which the carrier stream flows. Such a sample inlet arrangement will be described hereinafter.

A sample inlet into a carrier stream, such as a carrier stream flowing through a gas chromatograph system, is illustrated in FIG. 4. The heated sample injection port shown in FIG. 4 is similar to the injection port and chamber disclosed in U.S. Pat. No. 3,327,520 issued in the name of A. C. Stapp, Jr. on June 27, i967, and assigned to the same assignee as the present application. This sample injection port provides a means for vaporizing a liquid sample inserted into the apparatus by a sample injection device, such as the device of the present invention. In the gas chromatograph apparatus of FIG. 4, there is included a pressure regulator or flow controller 36, a sample injection vaporization port or device 37, a chromatograph column 38, or system of columns, adapted to receive the volatilized sample from the injection apparatus and a detector 39. A stream of carrier gas or fluid, ordinarily helium, although other fluids such as argon, nitrogen, carbon dioxide, hydrogen and even air may be used, is introduced into and controlled by the flow controller 36. At a particular time, a quantity of sample is injected into the injection port 37 and volatilized therein. The sample is then swept from the injection port through the column 38 where the sample constituents are separated. These constituents then enter the detector 39 which provides an output indication of the presence of the individual sample constituents as they emerge from the column 38.

The sample injection and vaporization port or device 37 is closed at its inlet 41 by a self-sealing cap or rubber septum 42 of the type commonly employed for sealing an opening to be punctured by a syringe needle. The rubber septum 42 is sealed across the opening 41 and retained thereon by a retainer cap 43 which may be removed to permit replacement of new septums. The port is formed of a block, or group of members forming a block, having a chamber 44 therein through which heated carrier gas may flow. In order to heat the carrier gas within the block 37, the carrier stream is forced to flow through a heated region within the block 37. Heat is supplied by any suitable means, such as electrical resistance heating rods 45, or any suitable source of energy such as hot gases or steam, whichever is desired. As may be seen in FIG. 4, the carrier gas is forced to flow through the passage 46, formed in the block, where it is heated and into the chamber 44 which is maintained at an extremely high temperature for further heating the carrier gas and vaporizing a sample as it is injected into the sample inlet end 38a of column 38. In this embodiment of the invention the column 38 extends upwardly into the sample injection and vaporization device and is sealed therein by a suitable sealing means such as the tube fitting 47, resilient gasket 48 and retainer 49 respectively. In this embodiment of the invention, the upper end 38a of the tub or chromatograph column is flared outwardly to from a conical shaped section adapted to receive the conically shaped shoulder or 32a of the sample injection device.

It will be understood that carrier gas, which is conducted into the chamber 44, normally enters the column 38 through its flared end 38a. When the sample injection device is inserted through the septum 42, the injector needle 11 extends downwardly into the upper end of the column and the shoulder 15 is moved into sealing relationship against the flared end 38a of the column. This blocks the flow of carrier gas through the open end of the column. The carrier gas is, at this point in time, partially or totally blocked from entering the flared end of the column. Therefore, the head pressure of the column will decrease slightly and the pressure within the chamber 44 will increase. At this time, the piston or plunger is retracted slightly thereby opening the inlet 16 into the sample cavity of the injection device. Carrier gas will then flow through the port 22 and sweep through the sample cavity 13 flushing out all of the sample within the sample cavity. The heated carrier gas flowing through the sample cavity forces the entire sample into the inlet end of the column 38, where it is immediately vaporized and caused to flow through the chromatograph column. Because carrier gas flows directly through the sample chamber, the chamber is completely swept by the hot carrier gas and no sample constituents can remain therein. There is immediate injection and vaporization of the liquid sample which sweeps through the sample cavity 13. This substantially eliminates the fractionation effect because all of the heavy constituents are vaporized by the hot carrier stream.

While the embodiments shown in FIGS. 1-3 illustrate the opening and closing of the port 16 by means of a plunger which is reciprocated by turning the plunger and threading it inwardly and outwardly, other means may be employed for reciprocating the plunger. In FIG. 5 there is disclosed another embodiment of the invention in which the plunger is reciprocated by a mechanical device adapted to move the plunger more quickly inwardly and outwardly without rotating it. In this embodiment of the invention, the plunger is reciprocated within the plunger cavity 17 by means of a spring biased lever system adapted to quickly move the plunger into its sealing position on release of a lever 51. Lever 51 is attached to the upper guide block 52 by means of a hinge 53. The upper arm 51a of the lever extends through a notch 54 formed in an extension 55 protruding from the top of the plunger 18. Spring 56 forces the lever arm outwardly thereby depressing the arm 51a against the lower edge of notch 54 causing the plunger 19 to seal against the opening 16 when the lever is in its normal position. When the lever arm 51 is pivoted around the pivot point of the hinge 53, against the normal pressure of spring 56, to compress the lower portion of the lever arm against the force of spring 56, the pressure on piston 18 is released and a second spring 58, supported within the guide member 59, causes the plunger to be moved upwardly away from its sealed position against the opening 16. The force of spring 58 is sufficient to cause the plunger to move into its retracted position. By quickly depressing spring 56 it is possible to very quickly release the seal produced by the tip 21 and thereby provide a communication between the opening 22 through the plunger cavity 17 into the opening 16 of the sample cavity.

While the embodiment illustrated in FIG. 4 shows one example of an inlet adapted to receive the injection apparatus within the flared end 38a of the chromatograph column, it is not essential that the inlet opening necessarily be the flared end of a chromatograph tube. Other means may be employed. For example, the sealing shoulder within the sample inlet may possibly be a formedshoulder within the tubular cavity 44 rather than a flared end of the tube. Or, for example, the shoulder may be a beaded or rolled portion formed within the tube a distance from the inlet end thereof into which both the needle portion of the injector and the shoulder will fit. An example of such an arrangement is illustrated in FIG. 6 in which the tubular injection port 61 is shown with an inwardly turned head 62 formed around the circumference thereof a short distance from the end 63 of the tube. The injection needle of the sample injection device extends into the opening 63 of the tube and the shoulder abuts against the shoulder 62 forming a seal against gas flowing through the tube 61. When this occurs the carrier stream is diverted through the port 22 and the opening 16 into the sample cavity 13 thereby forcing the liquid sample from the injection cavity.

While in accordance with the patent statutes there has been described what at present are considered to be the preferred embodiments of the invention, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, the aim of the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

1. A syringe-type sample injection apparatus adapted to be inserted through a self-sealing septum in a sample injection inlet of an analysis instrument for introducing a predetermined volume of fluid sample into a fluid stream flowing through the injection inlet comprising:

a support block, said support block including an axial bore therethrough, said axial bore having threads formed therein;

a tubular member including a forward needle section and a rearward plunger section, said tubular member extending from said support block and being supported thereby at one end of said rearward plunger section;

said needle section including a hollow needle having an axial sample cavity of predetermined volume and diameter, said cavity having a discharge opening at one end thereof and an inlet opening at the other end thereof;

said plunger section being attached to said needle section and having a plunger cavity aligned with said inlet opening of said sample cavity and said axial bore in said support block, said plunger section having a stream inlet port through the sidewall thereof, said inlet port being positioned in said sidewall closely adjacent said inlet opening to said sample cavity and communicating with said sample cavity in said needle section through said plunger cavity;

a plunger slidably positioned in said plunger section, said plunger having a tip adapted to abut upon and close said inlet opening to said sample cavity when said plunger is in a forward position and to open said inlet opening for communication with said stream inlet port when said plunger is in a retracted position;

a piston attached to said plunger and extending through said plunger cavity into said support block, said piston including a threaded section adapted to mate with said threads of said axial bore of said support block whereby said piston and said plunger may be moved inwardly and outwardly with respect to said opening in said cavity by rotat-- ing said piston; and a conically shaped shoulder formed on the outer surface of said needle section at a position between said discharge opening thereof and said inlet opening to said cavity in inlet of an analysis instrument for introducing a predetermined volume of fluid sample into a fluid stream flowing through the injection inlet comprising:

a tubular member including a forward needle section and a rearward plunger section;

said needle section including a hollow needle having'an I axial sample cavity of predetermined volume and diameter, said cavity having a discharge opening at one end thereof and an inlet opening at the other end thereof;

said plunger section being attached at one end to said needle section and having a plunger cavity aligned with said inlet opening to said sample cavity, said plunger section having a stream inlet port through the sidewall thereof, said inlet port being positioned in said sidewall closely adjacent to said inlet opening to said sample cavity and communicating with said sample cavity in said needle section through said plunger cavity;

a plunger slidably positioned in said plunger section, said plunger having a tip adapted to abut upon and close said inlet opening to said sample cavity when said plunger is in a forward position and to open said inlet opening for communication with said stream inlet port when said plunger is in a retracted position;

a piston attached to said plunger and extending through said plunger cavity and out the end of said plunger section not attached to said needle section;

sealing means around said piston for sealing between said piston and the sidewall of said plunger cavity;

means engaging said end of said piston extending out said plunger cavity for reciprocating said piston and said plunger between said forward and a retractedposition; and

a shaped shoulder formed on the outer surface of said nee-- dle section at a position between said discharge opening thereof and said inlet opening to said cavity in said needle section.

3. The sample injection apparatus defined in claim 2 in which said shaped shoulder comprises a conically shaped surface formed around the circumference of said needle section of said tubular member.

4. A sample injection apparatus for introducing a predetermined volume of fluid sample into a sample injection inlet of a gas analysis apparatus through which there flows a fluid stream, the sample inlet having an injection opening through which said fluid stream must flow, comprising:

a tubular member including a forward needle section and a rearward plunger section;

said needle section including a hollow needle adapted to be inserted into a sample inlet and having an axial sample cavity of predetermined volume and diameter, said cavity having a discharge opening at one end of said needle section and an inlet opening at the other end of said needle section;

said plunger section being attached to said needle section and having a plunger cavity aligned with said inlet opening to said sample cavity, said plunger section having a stream inlet port through the sidewall thereof adjacent said inlet opening to said needle section;

a plunger slideably positioned in said plunger section, said plunger having a valve tip adapted to abut of close said inlet opening to said sample cavity when said plunger is in a forward position and to open said inlet opening for communication with said stream inlet port when said plunger is in a retracted position;

means in said plunger section for reciprocating said plunger between said forward and retracted positions;

a shoulder formed on the outer surface of said needle section, said shoulder being so constructed and arranged on said needle section as to abut against said injection opening in the sample inlet thereby obstructing flow of the gas stream therethrough so that the gas stream is caused to flow through said stream inlet port of said plunger section into said sample cavity thereby to sweep a sample from said sample cavity when said plunger is retracted from said inlet opening to said sample cavity.

5. in combination:

a gas chromatograph system having a sample injection inlet including an injection port through which a stream of carrier gas must flow in its path toward remaining components of said gas chromatograph, said injection inlet having an opening closed by a self-sealing septum;

a sample injection device including a tubular member having a forward needle section and a rearward plunger section;

said needle section including a hollow needle having an axial sample cavity of predetermined volume and diameter, said cavity having a discharge opening at one end thereof and an inlet opening at the other end thereof, said needle section being of a size adapted to puncture said septum thereby permitting said needle section and at least a portion of said plunger section to be inserted into the injection port in the sample injection inlet of said chromatograph system, a shoulder formed on the outer surface of said needle section and being so constructed and arranged on said needle section as to abut against the injection port in said sample inlet thereby obstructing flow of the gas stream therethrough;

said plunger section being attached to said needle section and having a plunger cavity aligned with said inlet opening to said sample cavity, said plunger section having a gas stream inlet port through the sidewall thereof, said inlet port being positioned in said sidewall closely adjacent to and communicating with said inlet opening to said needle section through said plunger cavity;

a plunger slidably positioned in said plunger section, said plunger having a tip adapted to abut upon and close said inlet opening to said sample cavity when said plunger is in a forward position and to open said inlet opening for communication with said stream inlet port when said plunger is in a retracted position. so that the carrier gas stream is caused to flow through said sample cavity thereby to sweep a sample from said cavity; and means attached to said plunger section for reciprocating said plunger between said forward said retracted positions. 6. The combination defined in claim 5 in which said injection port has a beveled surface and said shoulder on said needle section of said sample injection device is conically shaped to mate. with the beveled surface of said injection port when said needle section is inserted into said injection port.

7. The combination defined in claim 5 in which said injection port comprises the end of a chromatograph column having an outwardly flared end surface and said shoulder on said needle section of said sample injection device includes a conically shaped surface shaped to mate with the flared end surface of said chromatograph column when said needle section is inserted into said injection port formed by the end of said column.

8. A syringe-type sample injection apparatus adapted to be inserted through'a self-sealing septum in a sample injection inlet of an analysis instrument for introducing a predetermined volume of fluid sample into a fluid stream flowing through the injection inlet comprising:

a tubular member including a forward needle section and a rearward plunger section;

said needle section including a hollow needle having an axial sample cavity of predetermined volume and a diameter, said cavity having a discharge opening at one end thereof and an inlet opening at the other end thereof;

said plunger section being attached at one end of said needle section and having a plunger cavity aligned with said inlet opening to said sample cavity, said plunger section having a stream inlet port through the sidewall thereof, said inlet port communicating with said inlet opening to said sample cavity through said plunger cavity;

a plunger slidably positioned in said plunger section, said plunger having a tip adapted to close said inlet opening to said sample cavity when said plunger is in a forward position and to open said inlet opening for communication with said stream inlet port when said plunger is in a retracted position;

a piston attached to said plunger and extending through said plunger cavity and out the end of said plunger section not attached to said needle section;

sealing means around said piston for sealing between said piston and the sidewall of said plunger cavity;

means attached to the end of said piston extending out of said plunger section for reciprocating said piston including a hinged lever attached to the upper portion of said tubular member and engaging said piston, said lever being spring biased in a direction causing said piston and said plunger attached thereto to be normally disposed in a for ward position closing said opening to said sample cavity;

spring means exerting a force on said piston in a direction adapted to move said piston and said plunger into a retracted position when said spring lever is operated against said spring force exerted thereon; and

a shaped shoulder formed on the outer surface of said needle section at a position between said discharge opening thereof and said inlet opening to said cavity and said needle section.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, September 14,

Inventor heron Johns It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 7, Line 9, change "of" to read upon and Signed and sealed this 30th day of May 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOT'ISGHALK Attesting Officer Commissioner of Patents 

1. A syringe-type sample injection apparatus adapted to be inserted through a self-sealing septum in a sample injection inlet of an analysis instrument for introducing a predetermined volume of fluid sample into a fluid stream flowing through the injection inlet comprising: a support block, said support block including an axial bore therethrough, said axial bore having threads formed therein; a tubular member including a forward needle section and a rearward plunger section, said tubular member extending from said support block and being supported thereby at one end of said rearward plunger section; said needle section including a hollow needle having an axial sample cavity of predetermined volume and diameter, said cavity having a discharge opening at one end thereof and an inlet opening at the other end thereof; said plunger section being attached to said needle section and having a plunger cavity aligned with said inlet opening of said sample cavity and said axial bore in said support block, said plunger section having a stream inlet port through the sidewall thereof, said inlet port being positioned in said sidewall closely adjacent said inlet opening to said sample cavity and communicating with said sample cavity in said needle section through said plunger cavity; a plunger slidably positioned in said plunger section, said plunger having a tip adapted to abut upon and close said inlet opening to said sample cavity when said plunger is in a forward position and to open said inlet opening for communication with said stream inlet port when said plunger is in a retracted position; a piston attached to said plunger and extending through said plunger cavity into said support block, said piston including a threaded section adapted to mate with said threads of said axial bore of said support block whereby said piston and said plunger may be moved inwardly and outwardly with respect to said opening in said cavity by rotating said piston; and a conically shaped shoulder formed on the outer surface of said needle section at a position between said discharge opening thereof and said inlet opening to said cavity in said needle section.
 2. A syringe-type sample injection apparatus adapted to be inserted through a self-sealing septum in a sample injection inlet of an analysis instrument for introducing a predetermined volume of fluid sample into a fluid stream flowing through the injection inlet comprising: a tubular member including a forward needle section and a rearward plunger section; said needle section including a hollow needle having an axial sample cavity of predetermined volume and diameter, said cavity having a discharge opening at one end thereof and an inlet opening at the other end thereof; said plunger section being attached at one end to said needle section and having a plunger cavity aligned with said inlet opening to said sample cavity, said plunger section having a stream inlet port through the sidewall thereof, said inlet port being positioned in said sidewall closely adjacent to said inlet opening to said sample cavity and communicating with said sample cavity in said needle section through said plunger cavity; a plunger slidably positioned in said plunger section, said plunger having a tip adapted to abut upon and close said inlet opening to said sample cavity when said plunger is in a forward position and to open said inlet opening for communication with said stream inlet port when said plunger is in a retracted position; a piston attached to said plunger and extending through said plunger cavity and out the end of said plunger section not attached to said needle section; sealing means around said piston for sealing between said piston and the sidewall of said plunger cavity; means engaging said end of said piston extending out said plunger cavity for reciprocating said piston and said plunger between said forward and a retracted position; and a shaped shoulder formed on the outer surface of said needle section at a position between said discharge opening thereof and said inlet opening to said cavity in said needle section.
 3. The sample injection apparatus defined in claim 2 in which said shaped shoulder comprises a conically shaped surface formed around the circumference of said needle section of said tubular member.
 4. A sample injection apparatus for introducing a predetermined volume of fluid sample into a sample injection inlet of a gas analysis apparatus through which there flows a fluid stream, the sample inlet having an injection opening through which said fluid stream must flow, comprising: a tubular member including a forward needle section and a rearward plunger section; said needle section including a hollow needle adapted to be inserted into a sample inlet and having an axial sample cavity of predetermined volume and diameter, said cavity having a discharge opening at one end of said needle section and an inlet opening at the other end of said needle section; said plunger section being attached to said needle section and having a plunger cavity aligned with said inlet opening to said sample cavity, said plunger section having a stream inlet port through the sidewall thereof adjacent said inlet opening to said needle section; a plunger slideably positioned in said plunger section, said plunger having a valve tip adapted to abut of close said inlet opening to said sample cavity when said plunger is in a forward position and to open said inlet opening for communication with said stream inlet port when said plunger is in a retracted position; means in said plunger section for reciprocating said plunger between said forward and retracted positions; a shoulder formed on the outer surface of said needle section, said shoulder being so constructed and arranged on said needle section as to abut against said injection opening in the sample inlet thereby obstructing flow of the gas stream therethrough so that the gas stream is caused to flow through said stream inlet port of said plunger section into said sample cavity thereby to sweep a sample from said sample cavity when said plunger is retracted from said inlet opening to said sample cavity.
 5. In combination: a gas chromatograph system having a sample injection inlet including an injection port through which a stream of carrier gas must flow in its path toward remaining comPonents of said gas chromatograph, said injection inlet having an opening closed by a self-sealing septum; a sample injection device including a tubular member having a forward needle section and a rearward plunger section; said needle section including a hollow needle having an axial sample cavity of predetermined volume and diameter, said cavity having a discharge opening at one end thereof and an inlet opening at the other end thereof, said needle section being of a size adapted to puncture said septum thereby permitting said needle section and at least a portion of said plunger section to be inserted into the injection port in the sample injection inlet of said chromatograph system, a shoulder formed on the outer surface of said needle section and being so constructed and arranged on said needle section as to abut against the injection port in said sample inlet thereby obstructing flow of the gas stream therethrough; said plunger section being attached to said needle section and having a plunger cavity aligned with said inlet opening to said sample cavity, said plunger section having a gas stream inlet port through the sidewall thereof, said inlet port being positioned in said sidewall closely adjacent to and communicating with said inlet opening to said needle section through said plunger cavity; a plunger slidably positioned in said plunger section, said plunger having a tip adapted to abut upon and close said inlet opening to said sample cavity when said plunger is in a forward position and to open said inlet opening for communication with said stream inlet port when said plunger is in a retracted position, so that the carrier gas stream is caused to flow through said sample cavity thereby to sweep a sample from said cavity; and means attached to said plunger section for reciprocating said plunger between said forward said retracted positions.
 6. The combination defined in claim 5 in which said injection port has a beveled surface and said shoulder on said needle section of said sample injection device is conically shaped to mate with the beveled surface of said injection port when said needle section is inserted into said injection port.
 7. The combination defined in claim 5 in which said injection port comprises the end of a chromatograph column having an outwardly flared end surface and said shoulder on said needle section of said sample injection device includes a conically shaped surface shaped to mate with the flared end surface of said chromatograph column when said needle section is inserted into said injection port formed by the end of said column.
 8. A syringe-type sample injection apparatus adapted to be inserted through a self-sealing septum in a sample injection inlet of an analysis instrument for introducing a predetermined volume of fluid sample into a fluid stream flowing through the injection inlet comprising: a tubular member including a forward needle section and a rearward plunger section; said needle section including a hollow needle having an axial sample cavity of predetermined volume and a diameter, said cavity having a discharge opening at one end thereof and an inlet opening at the other end thereof; said plunger section being attached at one end of said needle section and having a plunger cavity aligned with said inlet opening to said sample cavity, said plunger section having a stream inlet port through the sidewall thereof, said inlet port communicating with said inlet opening to said sample cavity through said plunger cavity; a plunger slidably positioned in said plunger section, said plunger having a tip adapted to close said inlet opening to said sample cavity when said plunger is in a forward position and to open said inlet opening for communication with said stream inlet port when said plunger is in a retracted position; a piston attached to said plunger and extending through said plunger cavity and out the end of said plunger section not attached to said needle section; sealing means around said piston for sealing between said piston and the sidewall of said plunger cavity; means attached to the end of said piston extending out of said plunger section for reciprocating said piston including a hinged lever attached to the upper portion of said tubular member and engaging said piston, said lever being spring biased in a direction causing said piston and said plunger attached thereto to be normally disposed in a forward position closing said opening to said sample cavity; spring means exerting a force on said piston in a direction adapted to move said piston and said plunger into a retracted position when said spring lever is operated against said spring force exerted thereon; and a shaped shoulder formed on the outer surface of said needle section at a position between said discharge opening thereof and said inlet opening to said cavity and said needle section. 